Hummingbirds are tiny, iridescent powerhouses. But some species are
catastrophically rare: we need to work to save them, says poet Ruth Padel.

I have been fascinated by hummingbirds ever since I was given a pack of wild animal cards in hospital while my tonsils were removed and fell in love with Heliothrix aurita, a speck of fire and jade. And also wine-red Topaza pella, perched in a jungle whisking a crimson tail.

I still have those cards. Their pictures seem crude now, but when I was eight I was enraptured. The Aztecs said the Earth’s first flower was fathered by the god of poetry in the shape of a hummingbird; and everything about hummingbirds seems tailor-made for a poet.

Birds see ultraviolet light, and female hummingbirds have a taste for iridescence, so males have turned themselves into flying jewels. Their metallic sheens, glancing as soap bubbles, are reflected in equally iridescent names for which taxonomists have plundered all the shimmer in the lexicon.

There are more than 300 species: words such as emerald, copper, bronze, gold, fire, sapphire, lazuline, emerald and sunbeam spill like Aladdin’s treasure through the list: amethyst woodstar, blue-headed sapphire, Brazilian ruby, buff-winged starfrontlet – you marvel not only at nature’s capacity for spangly variation but the human urge to match it in language.

Hummingbird nests – the size of a nutshell, spun out of plant down, covered with lichen, bound by spider’s silk – are works of art straight out of A Midsummer Night’s Dream. Hummingbird tongues, almost transparent, are liquid-trapping miracles of bioengineering that change shape as they flick in and out of the nectar. Their tips are forked: the V’s inside edges have feathery tufts that draw in nectar by capillary action. When hummingbirds sleep they fall into hibernation-like torpor. Metabolism drops, temperature zooms to near-hypothermic levels and breathing slows so drastically that if you find a sleeping hummingbird you think it’s dead. Which, in the Peruvian Andes, makes it a symbol of resurrection.

This sleep saves them desperately needed energy, for smaller hummingbirds may sip 1,500 flowers a day, and beating your wings 80 times a second burns a lot of calories. Those wings, connected to their body only at the shoulder joint, rotate 180° so the birds can not only hover vertically to feed but also fly backwards and upside down. Thirty per cent of their weight is flight muscles; four per cent is brain, the largest proportion for all birds, so they are the world’s most intelligent bird – well, for their size.

But they are not as sweet as they look. Hummingbirds are loners, extravagantly territorial. Rival males body-slam each other mid-air and lock beaks, spinning in a circle until they hit the ground. Males show off their colours to a female by flashing their feathers, zooming 60ft into the air and diving down to an inch above her head. They do this to chase off predators, too, so the female needs strong nerves: she is courted by aerial displays that can see off a hawk.

Hummingbirds live wild only in the Americas and Caribbean, mostly in tropical and subtropical forests in Central and South America. But there are some in the Andes and at least 20 species in the United States – including the ruby-throated hummingbird, which migrates for winter over the Gulf of Mexico. Each one, the size and weight of a 2½in paper clip, skims non-stop over 500 miles of open water, entirely alone.

The smallest of all, the bee hummingbird or zunzuncito, the size of a bumblebee, lives in Cuba. When my daughter was working there, I asked her to look out for one. “No problem,” she emailed. “It’s everywhere. They call it the zun-zun.” She went on to Colombia, the most biodiverse country for birds in the world, which has 160 different hummingbirds. When I visited, she took me into the Cocora Valley and up a mountain into cloud forest.

The trails were steep and rocky, but the hummingbirds at the top were worth it all. Cocora has six or eight species: we saw the buff-tailed coronet, the long-tailed sylph and a black iridescent bird that turned to fire as it flew.

In June 1832, Charles Darwin watched hummingbirds on a cliff path around Botafogo Bay in Brazil. “I counted four species,” he wrote in his journal. “The wings moved so rapidly that they were scarcely visible & remaining stationary the little bird darted its beak into the wild flowers making an extraordinary buzzing noise with its wings. Those I have met frequent shaded forests & may there be seen chasing away the rival butterfly.”

Before he set out on HMS Beagle, Darwin was elected a Corresponding Member of the Zoological Society of London (ZSL), founded five years before. Its zoo was one of the world’s first scientific zoos (after Jardin des Plantes in Paris), where scientists could study animals. He later served on its council. A hundred years later, his journal was edited by his granddaughter Nora Barlow. Gardeners may know her as the creator of aquilegia 'Nora Barlow’. She was my grandmother: her influence made wild nature vital for all of our family. When my throat recovered, I begged to see hummingbirds, and it was natural for my mother to take us to the zoo.

The tropical bird house we saw then was demolished 30 years ago, for zoos have changed drastically since Victorian times. As scientific knowledge of animal biology and animal needs improved, zoos started keeping animals in more natural surroundings, with better diets. To satisfy the needs of the Amazilia hummingbird today, ZSL’s keepers sterilise feeders twice a day, make fresh nectar and breed thousands of fruit flies daily. Hummingbirds are difficult to look after properly, and you need a good reason to try. These days the only reason to keep any wild animal is conservation — and conservation is the point of ZSL.

In the Seventies and Eighties, as wild habitats shrank and wild species began to disappear, zoos that took their role in society seriously realised their raison d’être had to be conservation. Now, as human populations explode, forests vanish and the integrity of the planet’s biological systems is under threat, modern zoos are a vital part of the conservation toolkit.

Not all of today’s visitors paying entry fees in Regent’s Park realise that what they are funding is a world-class Institute of Zoology, which trains future conservationists, and also a global conservation programme that protects wild habitats as well as wild animals in more than 50 countries. Equally, many people who never go to ZSL London Zoo but do care about “nature” don’t realise they are failing to support one of Britain’s leading nature conservation charities, which looks after animals and habitats on every continent: protecting tigers in Bangladesh or marine life in the Indian Ocean archipelago of Chagos, and restoring the corncrake to the English countryside.

This summer I’m curating a series of writers’ talks on endangered species to help highlight ZSL’s conservation. Each writer reads a piece on an endangered animal, partnered by a top conservation scientist who explains what ZSL is doing to protect its wild cousins. The animal goes about its business; keepers are on hand to answer questions over a glass of wine. Novelist and poet Mark Haddon talks about Galapagos tortoises, author Andrew O’Hagan explores his affinity with Malayan tapirs.

I shall talk on hummingbirds and other tropical birds in the new tropical pavilion. Most of these are endangered, some critically. Some are already extinct in the wild. My scientist partner will be the director of ZSL’s Institute of Zoology, Prof Tim Blackburn, whose research includes invasive species and how they hasten the extinction of native birds. The free-flying pavilion, central to conservation breeding programmes, really is an ark.

The first European to mention hummingbirds, Gonzalo Fernández de Oviedo y Valdés, said in 1526 their colours shone “like little birds painted to illuminate the margins of holy books”. Today, ZSL Conservation is working to make sure that the forests where Darwin saw them chasing butterfly rivals are safe. That neither hummingbirds nor their homes fade into illuminated memory on the margins of the Earth.

Ruth Padel is a Member of ZSL Council. She will be talking about tropical birds at ZSL London Zoo on July 16. To book for ZSL writers’ talks on endangered animals, see ZSL or telephone 0844 225 1826 Mon-Fri (8.30am-5pm)